compiler: fix double evaluation with interface field expression
compiler: fix double evaluation with interface field expression

In Interface_field_reference_expression, the interface expression
is used in two places, so a temporary variable is used. Previously,
we used a Set_and_use_temporary_expression, which, when evaluated
twice, causes double evaluation of the underlying expression. Fix
by setting the temporary once and use Temporary_reference_expression
instead.

Fixes golang/go#26248.

Change-Id: Ieec464201a5498c3c8c4a1751c3bb79f4a2b515c
Reviewed-on: https://go-review.googlesource.com/122756
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/gofrontend,golang/gofrontend,golang/gofrontend,golang/gofrontend